Peter Parrish wrote:
Bill,
I looked into this several years ago, and I was able to get some digitized
I-V data. I can't find that now (but I will). The data supports my claim.
Vmp does change with irradiance. It just changes very little. Depends
on your definition of "change" I guess.
Negligible I would say... That is, assuming a higher irradiance than
"dark" of course.
I can see where some confusion might come from from irradiance and PV
parameter variation... As the irradiance
changes, the ratio of Vmp to Voc changes. Lower irradiance normally
makes the Vmp/Voc rise somewhat but only
because the Voc is changing.
Now, put two or more modules in series, then shade one of them and
that's something entirely different.
Here's a good paper with some good data on this subject. I also see
Bill Brooks contributed to this article,
http://photovoltaics.sandia.gov/docs/PDF/King%20SAND.pdf (the %20 is
a space)
And for temperatue relations, here's another good one:
http://photovoltaics.sandia.gov/docs/PDF/IEDFB5~1.pdf
boB
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